Control means



Jan. 15,1946. A. E. STAFFORD CONTROL MEANS Filed Jan. 11, 1945 INVENTOP 4.5. STAFFORD ATTORNEY Patented Jan. 15, 1946 UNITED STATES PATENT. OFFlCE CONTROL MEANS Alfred E. Stafl 'ord Bloomfleld, N. J., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application January 11, 1945, Serial No. 572,314

4 Claims. (01. goo-81.6

This invention relates to control means, and more particularly to a device for controlling the flow of a gas.

In various arts and especially in arts pertaining to the manufacture of evacuated bulbs and tubes such as are filled after evacuation with specific gases or mixtures of gases at predetermined pressures, it is a matter of considerable dimculty to maintain the pressure of the gas so supplied and to control the flow thereof to ensure delivery of enough and only enough to a pre-evacuated tube or bulb to produce therein accurately the predetermined desired pressure.

An object of the present invention is to provide a device to both indicate and be responsive to the pressure of gas in an evacuated article and to control the flow of a gas being supplied thereto in accordance with the pressure in question, the device being further capable of compensative adjustment to correspond to changes of barometric pressure.

With the above and other objects in view, the invention may be embodied in a gas flow control apparatus comprising a mercury manometer to be connected to a standard source of evacuation, a second mercury manometer to be connected to an evacuated hollow article, means to adjust simultaneously and equally the height of the mercury columns in the two manometers, means to compare the heights of the mercury columns in the two manometers, an electrical contact member in one manometer contactible by the upper part of the mercury column thereof, and means to make electrical connection the lower part of the last named mercury column.

Other objects and features of the invention will appear from the following detailed description of one embodiment thereof, taken in connection with the accompanying drawing in which the same reference numerals are applied to identical parts andin which Fig. '1 is a broken view in side elevation of an apparatus constructed in accordance with the invention; and

Fig. 2 is a broken view thereof in front elevation. i

The apparatus herein disclosed comprises an elongated vertical slab-like support 10 having at the bottom thereof, a horizontal shelf-like member ll rigidly secured thereto. At the top is a forwardly projecting hood 12 housing a light bulb M to illuminate the front side of the support I0 and the parts secured thereon, and connected by a cable 15 to a current supply means not shown. 0n the front face of the support I0 slidable on and between the guide rods.

is secured a pair of vertical parallel tubes 16 and 11 secured on the support by any suitable means, e. g., a metal strap 18. The tubes l6 and 11 are preferably of glass or other transparent material, e. g., of one of the transparent artificial resins. The lower portions of these tubes are bent somewhat forward and vertically down again as at l9 to stand spaced forwardly from and parallel to the support It). Forwardly projecting side wall members 20 and 2| are secured along the sides of the member ID and to the member H as shown. Vertical guide rods 22 and 23 are secured by brackets 24 and 25 on the inner faces of the walls 20 and 21 respectively and in the member II. A yoke 26 having its ends turned out and perforated to receive the rods 22 and 23 is vertically A tank 21 of metal is secured between the arms of the yoke to be lowered and lifted thereby. The crossbar 28 of the yoke is centrally perforated to pass freely a vertical threaded shaft 30 which engages a correspondingly threaded nut 29. The shaft 30 is hung from and journalled in a horizontal member 3|. A knurled knob 32 secured on the upper end of the shaft 30 and rotatably resting on the member 3| supports the shaft and affords a means for rotating the shaft 30 with the fingers to adjustably raise or lower the tank 21, which carries a pool 33 of mercury into which the open bottom ends of the tubes l6 and I1 extend. In the upper portion of the tube IS, a contact wire 34, preferably of tungsten, is sealed through the wall of the tube horizontally and turned down within the tube and formed with a point 35 adapted to make and break electrical contact with the convex meniscus surface of a column of the mercury 33 drawn up into the tube [6. The contact member 34 is connected by a suitable insulated conductor 38 to a conventional terminal device 31 mounted on the support III. A similar terminal device 38 is connected to the metal tank 21 and thus is electrically connected to the mercury pool 33 by a suitable insulated conductor 33. Behind the upper ends of the tubes l6 and 11 a suitably graduated reference scale 40 is mounted on the support 10. The contact member 34 and the scale 40 are so located that the tip of point 35 is level with the zero graduation at the bottom of the scale 40.

A particular procedure for which the apparatus described may be used is the supply to an evacuated electronic tube of a particular gas, e. g., argon, to fill the evacuated tube with the gas to a precisely predetermined degree of density of the gas. The tube I! which is a calibration and comparison tube is connected at its upper end to some vacuum pump or other source of constant degree evacuation which will create in the upper part of the tube I! the same degree of evacuation as that in an electronic tube to be filled with gas. In similar fashion, the upper part of the tube I6 is evacuated to the same degree. The mercury 33 from the tank 21, which is open to the atmosphere at its top, rises in the tubes 15 and I! to some point on the scale 40. By manipulation of the knurled knob 32 and consequent rotation of the screw 30, the tank 2! is raised or lowered until the mercury in the tubes i6 and ['1' stands as many graduations above the zero of the scale 40 as will represent the difierence between the pressures in an evac uated electron tube before and after filling with gas. The terminal binding posts 31 and 38 are connected into a circuit to actuate some suitable device to shut off the flow of gas from some supply thereof when the circuit is broken. An evacuated electron tube to be filled with gas is connected to the tube l6 and to the gas supply and the latter is adjusted to feed gas into the electron tube. At this time, the mercury in the tube l6 stands above the contact point 35, and the gas supply control circuit is closed through the mercury and the point 35 to allow the gas to flow. As the gas enters the electron tube connected to the top of the tube It, the tenuity of the vacuum therein is lessened and the mercury falls proportionately in the tube 16. When the meniscus of the mercury loses touch with the point 35, the circuit is broken, and the flow of gas into the electron tube is stopped with the pressure of this gas in the tube at the desired value. The filled tube is sealed off, the top of the tube I6 is evacuated, and a new electron tube to be filled is connected to the tube (6.

Preferably the comparison calibrating tube I1 is connected to the pump or other source of evacuation employed to evacuate the electron tubes to be gas filled so that the tenuity of the vacuum maintained in the tube I1 is constantly that of the tubes to be filled. This tube I! thus serves both as a comparison standard and as a detector of any malfunction in the evacuation of the tubes in question. Should a meteorological change occur, eiiecting a change of barometric pressure in the environment of the apparatus, both tubes i6 and I! will be equally afiected, the change is immediately detectable in the tube I1, and may be simultaneously compensated in both tubes by manipulation f the knob 32. Once the mercury in the tube i6 has been properly set at the correct height above the zero mark of the scale, interruption of the control current through the binding posts 31 and 38 as the mercury falls below the point 35 when the desired gas density is reached, is automatic, is not dependent upon an operators eyesight or care, and is effected in the same way time after time. The attendant or operator of the gas filling apparatus has then no control over the amount of gas supplied to any tube and the results are automatically repeatable.

What is claimed is:

1. Gas flow control apparatus comprising means to contain a pool of mercury, means to adjust the level of the pool up and down, an upright tube having the lower end thereof extending down into the containing means below the normal level of mercury therein and having both ends open, a. second upright tube having the lower end thereof extending down into the containing means below the normal level of mercury therein and having both ends open, means to compare the height of a mercury column in the one tube with the height of a mercury column in the other tube, means to connect the pool of mercury electrically into one side of an electric circuit, and a contact member within one of the tubes to be connected into the other side of the circuit.

2. Gas flow control apparatus comprising a container to hold a pool of mercury, means to adjust the container up and down, an upright tube having the lower end thereof extending down into the container below the normal level of mercury therein and having both ends open, a second upright tube having the lower end thereof extending down into the container below the normal level of mercury therein and having both ends open, a scale to compare the height of a mercury column in the one tube with the height of a mercury column in the other tube, means to connect the pool of mercury electrically into one side of an electric circuit, and a contact member within one of the tubes to be connected into the other side of the circuit.

3. Gas flow control apparatus comprising a metal container to hold a pool of mercury, means to adjust the container up and down, an upright tube having the lower end thereof extending down into the containing means below the normal level of mercury therein and having both ends open, a second upright tube having the lower end thereof extending down into the containing means below the normal level of mercury therein and having both ends open, a scale to compare the height of a mercury column in the one tube with the height of a mercury column in the other tube, means to connect the container electrically into one side of an electric circuit, and a contact member within one of the tubes to be connected into the other side of the circuit.

4. Gas flow control apparatus comprising a mercury manometer to be connected to a standard source of evacuation, a second mercury manometer to be connected to an evacuated hollow article, means to adjust simultaneously and equally the height of the mercury columns in the two manometers, means to compare the heights of the mercury columns in the two manometers, an electrical contact member in one manometer contactible by the upper part of the mercury column thereof, and means to make electrical connection to the lower part of the last named mercury column.

ALFRED E. STAFFORD. 

